Data and images displayed on STAR sites
are provided for experimental use only and are
not official operational NOAA products.
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STAR Satellite Rainfall Estimates

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Purpose of This Site

This page provides access to short-term rainfall products which are
produced in real-time at STAR, both in image and data formats. These
products are intended for use for short-term estimates of rainfall at
high spatial and temporal resolution; for climate applications, we
recommend other products such as CMORPH
which have a higher level of accuracy but have longer latency times.

Why Use Satellite Rainfall Estimates?

Rain gauges provide a direct measurement of rainfall; however, the
spatial density of rain gauge networks (especially of gauges whose data
are available in real time) is typically far too coarse to capture the
spatial variability of rainfall at small scales. Radar provides an
indirect measurement of rainfall, but only for regions within a few
hundred km of a radar unit - and even less in mountainous regions due to
blockage of the beam. Estimates of rainfall from satellite data are
less direct and less accurate than either gauges or radar, but have the
advantage of high spatial resolution (4 km) and complete coverage over
oceans, mountainous regions, and sparsely populated areas where other
sources of rainfall data are not available. Since flash flood events
often originate with heavy rainfall in sparsely instrumented areas that
goes undetected, satellite-derived rainfall can be a critical tool for
identifying hazards from smaller-scale rainfall and flood events.

Products

The current real-time rainfall products at STAR are:

The Hydro-Estimator (H-E),
which produces estimates based on GOES IR window brightness temperatures
and modifies them using numerical weather model data. The H-E has been the
operational algorithm at NESDIS since 2002. It is produced operationally
(24/7 support) over the CONUS, and experimentally (8/5 support) for the
rest of the world.